904L stainless steel pipe is one of the best stainless steel grades for corrosion resistance. This grade is written as 1.4539 or X1NiCrMoCu25-20-5 according to EN norm and it is written as UNS S08904 according to UNS norm. 904L stainless steel pipe grade contains a very high level of nickel, molybdenum, chromium, and combinations of all these elements making this stainless steel grade very well resistant to attacks in acidic environments, such as sulphuric, phosphoric, and acetic acid.
Production Specification
Standard:ASTM A409, A213, A312, A358, A790
OD : 10-1067mm
WT: 1-150mm
Length:1000-13000mm
Surface treatment: Mill finished, Polished.
904L Chemical composition:
| Weight % | C | And | Mn | S | P | Cr | In | Mo | Cu | N |
| Min. | 24,0 | 6,00 | 3,00 | 0,24 | ||||||
| Max. | 0,03 | 0,80 | 1,20 | 0,020 | 0,035 | 26,0 | 8,00 | 5,00 | 0,50 | 0,32 |
904L Mechanical Properties:
| Yield strength Rp0.2, MPa |
Tensile strength Rm, MPa |
Elongation [%] |
Hardness [HB] |
Impact, Charpy-V, -196ºC [J] |
| ≥ 230 | 520 – 720 | ≥ 35 | ≤ 90 | 60 |
904L PREN = (Cr% + 3.3Mo% + 16N%) ≥ 40
Corrosion Resistance
Although originally developed for its resistance to sulphuric acid it also has a very high resistance to a wide range of environments. A PRE of 35 indicates that the material has good resistance to warm seawater and other high chloride environments. High nickel content results in much better resistance to stress corrosion cracking than the standard austenitic grades. Copper adds resistance to sulphuric and other reducing acids, particularly in the very aggressive “mid concentration” range. In most environments, 904L has a corrosion performance intermediate between the standard austenitic grade 316L and the very highly alloyed 6% molybdenum and similar “super austenitic” grades. In aggressive nitric acid 904L has less resistance than molybdenum-free grades such as 304L and 310L. For maximum stress corrosion cracking resistance in critical environments, the steel should be solution treated after cold work. Consult Atlas Technical Assistance for specific environmental recommendations.
Heat Treatment
Solution Treatment (Annealing) Heat to 1090-1175°C and cool rapidly. This grade cannot be hardened by thermal treatment. Welding 904L can be successfully welded by all standard methods. Care needs to be taken as this grade solidifies fully austenitic, so is susceptible to hot cracking, particularly in constrained weldments. No pre-heat should be used and in most cases, post-weld heat treatment (PWHT) is also not required. Grade 904L rods and electrodes for welding of 904L.
Typical Applications
Processing plant for sulphuric, phosphoric, and acetic acids.
Pulp and paper processing.
Components in gas scrubbing plants.
Seawater cooling equipment.
Oil refinery components.
Wires in electrostatic precipitators.
